Drive device and vehicle

ABSTRACT

A drive device includes a motor, an inverter, an electric power storage device, and an electronic control unit. The electronic control unit is configured to generate a first pulse width modulation (PWM) signal of the switching elements by comparison of a voltage command of each phase according to a torque command of the motor and a carrier wave voltage, as a first PWM control. The electronic control unit is configured to generate a second PWM signal of the switching elements based on a modulation factor and a voltage phase of a voltage according to the torque command and a pulse count per unit cycle of an electric angle of the motor, as a second pulse width modulation control. The electronic control unit is configured to limit execution of the second PWM control when high controllability of the motor is requested rather than when the high controllability is not requested.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2016-205427 filed onOct. 19, 2016 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a drive device and a vehicle, and inparticular, a drive device including a motor, an inverter, and anelectric power storage device, and a vehicle in which the drive deviceis mounted.

2. Description of Related Art

In the related art, as a drive device, a drive device that includes anelectric motor, and an electric power conversion device having aninverter circuit configured to drive the electric motor by switching aplurality of switching elements, generates a pulse signal of theswitching elements based on a pulse count in one electrical cycle of theelectric motor and a modulation factor and a voltage phase of a voltageaccording to a torque command of the electric motor, and switches theswitching elements has been suggested (for example, see JapaneseUnexamined Patent Application Publication No. 2013-162660 (JP2013-162660 A)). In the drive device, the pulse signal is generated suchthat electric power loss of the electric power conversion device and theelectric motor is minimized based on the pulse count, the modulationfactor, and the voltage phase, thereby achieving reduction of loss ofthe entire drive device.

SUMMARY

In a method that generates the pulse signal and outputs the pulse signalto the electric power conversion device in the above-described drivedevice, it is considered that a switching frequency of the switchingelements is set to be smaller than in a method that generates a pulsesignal by comparison of a voltage command of each phase of an electricmotor and a carrier wave voltage and outputs the pulse signal to anelectric power conversion device. However, in a case where the switchingfrequency of the switching elements is set to be small, controllabilityof the electric motor is likely to be degraded. For this reason, thereis a possibility that the controllability of the electric motor isfurther degraded for any reason or there is a request for furtherenhancing the controllability of the electric motor, and accordingly,there is a possibility that the request is not satisfied when highcontrollability of the electric motor is requested.

The present disclosure provides a drive device and a vehicle thatsufficiently satisfy a request for controllability.

Aspects of the present disclosure are as follows.

A first aspect of the present disclosure relates to a drive deviceincluding a motor for traveling, an inverter, an electric power storagedevice, and an electronic control unit. The inverter is configured todrive the motor by switching a plurality of switching elements. Theelectric power storage device is configured to transmit and receiveelectric power to and from the motor through the inverter. Theelectronic control unit is configured to generate a first pulse widthmodulation (PWM) signal of the switching elements by comparison of avoltage command of each phase according to a torque command of the motorand a carrier wave voltage and switch the switching elements with thefirst PWM signal, as a first PWM control. The electronic control unit isconfigured to generate a second PWM signal of the switching elementsbased on a modulation factor and a voltage phase of a voltage accordingto the torque command and a pulse count per unit cycle of an electricangle of the motor and switch the switching elements with the secondpulse width modulation signal, as a second pulse width modulationcontrol. A switching frequency of the switching elements in the secondPWM control is set to be smaller than a switching frequency of theswitching elements in the first PWM control. The electronic control unitis configured to limit execution of the second PWM control when highcontrollability of the motor is requested rather than when the highcontrollability is not requested.

With the drive device of the first aspect, the execution of the secondPWM control is limited when the high controllability of the motor isrequested rather than when the high controllability is not requested.Since the second PWM control has the switching frequency of theswitching elements set to be smaller than in the first PWM control, thecontrollability of the motor is likely to be degraded. Accordingly, theexecution of the second PWM control as the control of the inverter islimited when the high controllability of the motor is requested ratherthan when the high controllability is not requested. With this, it ispossible to sufficiently satisfy the request for the highcontrollability of the motor. As the “limitation of the execution of thesecond PWM control”, reduction of an execution area of the second PWMcontrol, inhibition of the execution of the second PWM control, or thelike can be exemplified.

In the drive device according to the first aspect, the electroniccontrol unit may be configured to permit the execution of the second PWMcontrol when the high controllability is not requested, and to inhibitthe execution of the second PWM control when the high controllability isrequested. With this, it is possible to determine the execution orinhibition of the second PWM control according to whether or not thehigh controllability of the motor is requested. In this case, theelectronic control unit may be configured to execute the first PWMcontrol when a target operation point of the motor is outside apredetermined area even in a case where the high controllability is notrequested and the execution of the second PWM control is permitted. Withthis, it is possible to determine whether to permit or inhibit theexecution of the second PWM control as the control of the inverter, andto determine which of the first PWM control and the second PWM controlis to be executed according to the target operation point of the motor.

In the drive device according to the first aspect, the electroniccontrol unit may be configured to generate the second PWM signal of theswitching elements such that, in the second PWM control, a harmoniccomponent of a desired order is reduced and a total loss of loss of themotor and loss of the inverter is reduced more than in the first PWMcontrol. With this, in a case of executing the second PWM control, it ispossible to achieve reduction of a harmonic component of a desired orderor reduction of total loss more than in a case of executing the firstPWM control. The “desired order” may be a specific order, or may beorders in a comparatively wide range of a low order to a high order.

The drive device according to the first aspect may further include arotation position detection sensor configured to detect a rotationposition of a rotor of the motor, and a current sensor configured todetect a current flowing in the motor. The electronic control unit maybe configured to determine that the high controllability is requestedwhen zero learning of at least one of the rotation position detectionsensor and the current sensor is not completed. When the zero learningof the rotation position detection sensor or the current sensor is notcompleted, there is a possibility that the controllability of the motoris further degraded. Accordingly, when the zero learning of at least oneof the rotation position detection sensor and the current sensor is notcompleted, determination is made that the high controllability isrequested, and the execution of the second PWM control as the control ofthe inverter is limited. With this, it is possible to sufficientlysatisfy the request for the high controllability of the motor.

The drive device according to the first aspect may further include arotation position detection sensor configured to detect a rotationposition of a rotor of the motor, and a current sensor configured todetect a current flowing in the motor. The electronic control unit maybe configured to determine that the high controllability is requestedwhen an abnormality occurs in at least one of the rotation positiondetection sensor and the current sensor. When an abnormality occurs inthe rotation position detection sensor or the current sensor, there is apossibility that the controllability of the motor is further degraded.Accordingly, when an abnormality occurs in at least one of the rotationposition detection sensor and the current sensor, determination is madethat the high controllability is requested, and the execution of thesecond PWM control as the control of the inverter is limited. With this,it is possible to sufficiently satisfy the request for the highcontrollability of the motor.

In the drive device according to first aspect, the electronic controlunit may be configured to determine that the high controllability isrequested when an amount of change per unit time of at least one of thetorque command of the motor, a rotation speed of the motor, a voltage ofthe inverter, and a voltage of the electric power storage device isgreater than a corresponding threshold. When the torque command or therotation speed of the motor, the voltage of the inverter, or the voltageof the electric power storage device is rapidly changed (when a drivestate of the motor is rapidly changed), there is a possibility that thecontrollability of the motor is further degraded. Accordingly, when thetorque command or the rotation speed of the motor, the voltage of theinverter, or the voltage of the electric power storage device is rapidlychanged, determination is made that the high controllability isrequested, and the execution of the second PWM control as the control ofthe inverter is limited. With this, it is possible to sufficientlysatisfy the request for the high controllability of the motor.

In the drive device according to the first aspect, the electroniccontrol unit may be configured to determine that the highcontrollability is requested when vibration damping control by the motoris performed. When the vibration damping control by the motor isperformed, in order to sufficiently exhibit vibration dampingperformance, the controllability of the motor may be further enhanced(is requested to be further enhanced). Accordingly, when the vibrationdamping control by the motor is performed, determination is made thatthe high controllability is requested, and the execution of the secondPWM control as the control of the inverter is limited. With this, it ispossible to sufficiently satisfy the request for the highcontrollability of the motor.

The drive device according to the first aspect may further include aboost converter configured to boost electric power from the electricpower storage device and to supply electric power to the inverter, acurrent sensor configured to detect a current flowing in a reactor ofthe boost converter, and a voltage sensor configured to detect a voltageon the inverter from the boost converter. The electronic control unitmay be configured to determine that the high controllability isrequested when an abnormality occurs in at least one of the currentsensor and the voltage sensor. When an abnormality occurs in the currentsensor or the voltage sensor, there is a possibility that thecontrollability of the motor is further degraded. Accordingly, when anabnormality occurs in at least one of the current sensor and the voltagesensor, determination is made that the high controllability isrequested, and the execution of the second PWM control as the control ofthe inverter is limited. With this, it is possible to sufficientlysatisfy the request for the high controllability of the motor.

A second aspect of the present disclosure relates to a vehicle includingthe drive device according to the first aspect, drive wheels, an engine,a power generator, an inverter for a power generator, and a relay. Thedrive wheels are connected to the motor and driven. The power generatoris configured to generate electric power using power from the engine.The inverter for a power generator is configured to drive the powergenerator by switching a plurality of second switching elements. Therelay is configured to perform connection and disconnection of theinverter and the inverter for a power generator to and from the electricpower storage device. The electronic control unit is configured tocontrol the inverter for a power generator by switching the first PWMcontrol and the second PWM control. The electronic control unit isconfigured to determine that the high controllability of the motor andthe power generator is requested in a case of performing traveling bydisconnecting the inverter and the inverter for a power generator fromthe electric power storage device by the relay. The electronic controlunit is configured to limit the execution of the second PWM control whenthe high controllability of the power generator is requested rather thanwhen the high controllability is not requested. In a case of performingtraveling by disconnecting the inverter and the inverter for a powergenerator from the electric power storage device by the relay, the sumof the electric power consumption (generated electric power) of themotor and the power generator cannot be absorbed with the electric powerstorage device. For this reason, the sum of the electric powerconsumption of the motor and the power generator needs to be adjustedwith higher accuracy, and the controllability of the motor and the powergenerator needs to be further enhanced (is requested to be furtherenhanced). Accordingly, in a case of performing traveling bydisconnecting the inverter and the inverter for a power generator fromthe electric power storage device by the relay, determination is madethat the high controllability of the motor and the power generator isrequested, and the execution of the second PWM control as the control ofthe inverter is limited. With this, it is possible to sufficientlysatisfy the request for the high controllability of the motor.

A third aspect of the present disclosure relates to a vehicle includingthe drive device according to the first aspect, drive wheels, an engine,a motor generator, a planetary gear, and an inverter for a motorgenerator. The drive wheels are connected to the motor and driven. Theplanetary gear includes three rotating elements. The three rotatingelements of the planetary gear are connected to an output shaft of theengine, a rotational shaft of the motor generator, and a drive shaftcoupled to an axle, respectively. The inverter for a motor generator isconfigured to drive the motor generator by switching a plurality ofsecond switching elements. The electric power storage device isconnected to the motor and the motor generator through the inverter andthe inverter for a motor generator so as to transmit and receiveelectric power to and from the motor and the motor generator. Theelectronic control unit is configured to control the inverter for amotor generator by switching the first PWM control and the second PWMcontrol. The electronic control unit is configured to determine that thehigh controllability of the motor and the motor generator is requestedin a case of starting the engine by cranking the engine with the motorgenerator. The electronic control unit is configured to limit theexecution of the second PWM control when the high controllability of themotor generator is requested rather than when the high controllabilityis not requested. In a case of starting the engine by cranking theengine with the motor generator, the rotation speed or torque of themotor generator is changed comparatively largely, or the torque of themotor is rapidly changed in order to secure torque for traveling due torapid change in torque output from the motor generator and applied tothe drive shaft through the planetary gear. For this reason, there is apossibility that the controllability of the motor or the motor generatoris further degraded. Accordingly, in a case of starting the engine bycranking the engine with the motor generator, determination is made thatthe high controllability is requested, and the execution of the secondPWM control as the control of the inverter is limited. With this, it ispossible to sufficiently satisfy the request for the highcontrollability of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the present disclosure will be described belowwith reference to the accompanying drawings, in which like numeralsdenote like elements, and wherein:

FIG. 1 is a configuration diagram showing the outline of theconfiguration of a hybrid vehicle in which a drive device of an exampleis mounted;

FIG. 2 is a configuration diagram showing the outline of theconfiguration of an electric drive system including a motor;

FIG. 3 is an explanatory view showing an example of the relationshipbetween a pulse count in first PWM control and second PWM control, andtotal loss of loss of the motor and loss of an inverter;

FIG. 4 is a flowchart showing an example of a control-for-executionsetting routine that is executed by a motor ECU;

FIG. 5 is an explanatory view showing an example of the relationshipbetween a target operation point of the motor, and an area of the firstPWM control and an area of the second PWM control;

FIG. 6 is an explanatory view showing an example of a permission flagsetting routine that is executed by the motor ECU;

FIG. 7 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 8 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 9 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 10 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 11 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 12 is an explanatory view showing an example of a permission flagsetting routine of a modification example;

FIG. 13 is a configuration diagram showing the outline of theconfiguration of a hybrid vehicle of a modification example;

FIG. 14 is a configuration diagram showing the outline of theconfiguration of a hybrid vehicle of a modification example; and

FIG. 15 is a configuration diagram showing the outline of theconfiguration of an electric vehicle of a modification example.

DETAILED DESCRIPTION OF EMBODIMENTS

Next, a mode for carrying out the present disclosure will be describedin connection with an example.

FIG. 1 is a configuration showing the outline of the configuration of ahybrid vehicle 20 in which a drive device as an example of the presentdisclosure is mounted. FIG. 2 is a configuration diagram showing theoutline of the configuration of an electric drive system includingmotors MG1, MG2. As shown in FIG. 1, the hybrid vehicle 20 of theexample includes an engine 22, a planetary gear 30, motors MG1, MG2,inverters 41, 42, a battery 50 as an electric power storage device, aboost converter 55, a system main relay 56, and an electronic controlunit for hybrid (hereinafter, referred to as an “HVECU”) 70.

The engine 22 is constituted as an internal combustion engine thatoutputs power with gasoline, diesel, or the like as fuel. The engine 22is operated and controlled by an electronic control unit for an engine(hereinafter, referred to as an “engine ECU”) 24.

Though not shown, the engine ECU 24 is constituted as a microprocessorcentering on a CPU, and includes, in addition to the CPU, a ROM thatstores a processing program, a RAM that temporarily stores data, aninput/output port, and a communication port. Signals from varioussensors for operating and controlling the engine 22, for example, acrank angle θcr from a crank position sensor 23 that detects a rotationposition of a crankshaft 26 of the engine 22, and the like are input tothe engine ECU 24 through the input port. Various control signals foroperating and controlling the engine 22 are output from the engine ECU24 through the output port. The engine ECU 24 is connected to the HVECU70 through the communication port. The engine ECU 24 calculates arotation speed Ne of the engine 22 based on the crank angle θcr from thecrank position sensor 23.

The planetary gear 30 is constituted as a single-pinion type planetarygear mechanism. A rotor of the motor MG1 is connected to a sun gear ofthe planetary gear 30. A drive shaft 36 coupled to drive wheels 39 a, 39b through a differential gear 38 is connected to a ring gear of theplanetary gear 30. The crankshaft 26 of the engine 22 is connected to acarrier of the planetary gear 30 through a damper 28.

The motor MG1 is constituted as a synchronous motor generator having arotor embedded with a permanent magnet and a stator wound withthree-phase coils, and as described above, the rotor is connected to thesun gear of the planetary gear 30. Similarly to the motor MG1, the motorMG2 is constituted as a synchronous motor generator having a rotorembedded with a permanent magnet and a stator wound with three-phasecoils, and the rotor is connected to the drive shaft 36.

As shown in FIG. 2, the inverter 41 is connected to a high voltage-sidepower line 54 a. The inverter 41 has six transistors T11 to T16, and sixdiodes D11 to D16 connected in reversely parallel with the transistorsT11 to T16. The transistors T11 to T16 are disposed in pairs so as tobecome a source side and a sink side with respect to a positiveelectrode-side line and a negative electrode-side line of the highvoltage-side power line 54 a. The three-phase coils (U-phase, V-phase,and W-phase) of the motor MG1 are connected to connection points betweenthe paired transistors of the transistors T11 to T16, respectively.Accordingly, when a voltage is applied to the inverter 41, the ratio ofthe on time of the paired transistors of the transistors T11 to T16 isadjusted by an electronic control unit for a motor (hereinafter,referred to as a “motor ECU”) 40. With this, a rotating magnetic fieldis formed in the three-phase coils, and the motor MG1 is rotationallydriven. Similarly to the inverter 41, the inverter 42 is connected tothe high voltage-side power line 54 a, and has six transistors T21 toT26 and six diodes D21 to D26. Then, when a voltage is applied to theinverter 42, the ratio of the on time of the paired transistors of thetransistors T21 to T26 is adjusted by the motor ECU 40. With this, arotating magnetic field is formed in the three-phase coils, and themotor MG2 is rotationally driven.

The boost converter 55 is connected to the high voltage-side power line54 a, to which the inverters 41, 42 are connected, and a lowvoltage-side power line 54 b to which the battery 50 is connected. Theboost converter 55 has two transistors T31, T32, two diodes D31, D32connected in reversely parallel with the transistors T31, T32, and areactor L. The transistor T31 is connected to the positiveelectrode-side line of the high voltage-side power line 54 a. Thetransistor T32 is connected to the transistor T31 and negativeelectrode-side lines of the high voltage-side power line 54 a and thelow voltage-side power line 54 b. The reactor L is connected to aconnection point between the transistors T31, T32 and a positiveelectrode-side line of the low voltage-side power line 54 b. The ratioof the on time of the transistors T31, T32 is adjusted by the motor ECU40, whereby the boost converter 55 boosts electric power of the lowvoltage-side power line 54 b and supplies electric power to the highvoltage-side power line 54 a. The boost converter 55 deboosts electricpower of the high voltage-side power line 54 a and supplies electricpower to the low voltage-side power line 54 b. A smoothing capacitor 57is attached to the positive electrode-side line and the negativeelectrode-side line of the high voltage-side power line 54 a. Asmoothing capacitor 58 is attached to the positive electrode-side lineand the negative electrode-side line of the low voltage-side power line54 b.

Though not shown, the motor ECU 40 is constituted as a microprocessorcentering on a CPU, and includes, in addition to the CPU, a ROM thatstores a processing program, a RAM that temporarily stores data, aninput/output port, and a communication port. As shown in FIG. 1, signalsfrom various sensors for driving and controlling the motors MG1, MG2 orthe boost converter 55 are input to the motor ECU 40 through the inputport. As the signals that are input to the motor ECU 40, for example,rotation positions θm1, θm2 from rotation position detection sensors(for example, resolvers) 43, 44 that detect rotation positions of therotors of the motors MG1, MG2, and phase currents Iu1, Iv1, Iu2, Iv2from current sensors 45 u, 45 v, 46 u, 46 v that detect currents flowingin the phases of the motors MG1, MG2 can be exemplified. In addition, avoltage (a voltage of the high voltage-side power line 54 a) VH of thecapacitor 57 from a voltage sensor 57 a attached between the terminalsof the capacitor 57, a voltage (a voltage of the low voltage-side powerline 54 b) VL of the capacitor 58 from a voltage sensor 58 a attachedbetween the terminals of the capacitor 58, and a current IL flowing inthe reactor L from a current sensor 55 a attached to a terminal of thereactor L can be exemplified. A switching control signal to thetransistors T11 to T16, T21 to T26 of the inverters 41, 42, a switchingcontrol signal to the transistors T31, T32 of the boost converter 55,and the like are output from the motor ECU 40 through the output port.The motor ECU 40 is connected to the HVECU 70 through the communicationport. The motor ECU 40 calculates electric angles θ_(e1), θ_(e2),angular velocities ωm1, ωm2, and rotation speeds Nm1, Nm2 of the motorsMG1, MG2 based on the rotation positions θm1, θm2 of the rotors of themotors MG1, MG2 from the rotation position detection sensors 43, 44.

The battery 50 is constituted as, for example, a lithium-ion secondarybattery or a nickel-hydrogen secondary battery, and is connected to thelow voltage-side power line 54 b. The battery 50 is managed by anelectronic control unit for a battery (hereinafter, referred to as a“battery ECU”) 52.

Though not shown, the battery ECU 52 is constituted as a microprocessorcentering on a CPU, and includes, in addition to the CPU, a ROM thatstores a processing program, a RAM that temporarily stores data, aninput/output port, and a communication port. Signals from varioussensors for managing the battery 50 are input to the battery ECU 52through the input port. As the signals that are input to the battery ECU52, for example, a voltage Vb from a voltage sensor 51 a providedbetween the terminals of the battery 50, a battery current Ib from acurrent sensor 51 b attached to the output terminal of the battery 50,and a temperature Tb from a temperature sensor 51 c attached to thebattery 50 can be exemplified. The battery ECU 52 is connected to theHVECU 70 through the communication port. The battery ECU 52 calculates astate of charge SOC based on an integrated value of the battery currentIb from the current sensor 51 b. The state of charge SOC is the ratio ofthe capacity of electric power dischargeable from the battery 50 to thetotal capacity of the battery 50.

The system main relay 56 is provided on the battery 50 side from thecapacitor 58 in the low voltage-side power line 54 b. The system mainrelay 56 is controlled to be turned on and off by the HVECU 70, therebyperforming connection and disconnection of the battery 50 and the boostconverter 55.

Though not shown, the HVECU 70 is constituted as a microprocessorcentering on a CPU, and includes, in addition to the CPU, a ROM thatstores a processing program, a RAM that temporarily stores data, aninput/output port, and a communication port. Signals from varioussensors are input to the HVECU 70 through the input port. As the signalsthat are input to the HVECU 70, for example, an ignition signal from anignition switch 80 and a shift position SP from a shift position sensor82 that detects an operation position of a shift lever 81 can beexemplified. In addition, an accelerator operation amount Acc from anaccelerator pedal position sensor 84 that detects a depression amount ofan accelerator pedal 83, a brake pedal position BP from a brake pedalposition sensor 86 that detects a depression amount of a brake pedal 85,and a vehicle speed V from a vehicle speed sensor 88 can be exemplified.The shift position SP includes a parking position (P position), areverse position (R position), a neutral position (N position), aforward position (D position), and the like. As described above, theHVECU 70 is connected to the engine ECU 24, the motor ECU 40, and thebattery ECU 52 through the communication port.

The hybrid vehicle 20 of the example configured as above travels in ahybrid traveling (HV traveling) mode in which traveling is performedwith the operation of the engine 22, or in an electrically poweredtraveling (EV traveling) mode in which traveling is performed withoutthe operation of the engine 22.

In the HV traveling mode, the HVECU 70 set requested torque Td*requested for traveling (requested for the drive shaft 36) based on theaccelerator operation amount Acc and the vehicle speed V. Requestedpower Pd* requested for traveling (requested for the drive shaft 36) iscalculated by multiplying the set requested torque Td* by a rotationspeed Nd of the drive shaft 36 (the rotation speed Nm2 of the motorMG2). Subsequently, requested power Pe* requested for the vehicle(requested for the engine 22) is set by subtracting requestedcharge/discharge power Pb* (a positive value when electric power isdischarged from the battery 50) based on the state of charge SOC of thebattery 50 from the requested power Pd*. Next, a target rotation speedNe* or target torque Te* of the engine 22 and the torque commands Tm1*,Tm2* of the motors MG1, MG2 are set such that the requested power Pe* isoutput from the engine 22 and the requested torque Td* is output fromthe drive shaft 36. Subsequently, a target voltage VH* of the highvoltage-side power line 54 a (capacitor 57) is set based on the torquecommands Tm1*, Tm2* or the rotation speeds Nm1, Nm2 of the motors MG1,MG2. Then, the target rotation speed Ne* or the target torque Te* of theengine 22 is transmitted to the engine ECU 24, and the torque commandsTm1*, Tm2* of the motors MG1, MG2 or the target voltage VH* of the highvoltage-side power line 54 a is transmitted to the motor ECU 40. Theengine ECU 24 performs intake air amount control, fuel injectioncontrol, ignition control, and the like of the engine 22 such that theengine 22 is operated based on the target rotation speed Ne* and thetarget torque Te*. The motor ECU 40 performs switching control of thetransistors T11 to T16, T21 to T26 of the inverters 41, 42 such that themotors MG1, MG2 are driven with the torque commands Tm1*, Tm2*. Inaddition, the motor ECU 40 performs switching control of the transistorsT31, T32 of the boost converter 55 such that the voltage VH of the highvoltage-side power line 54 a becomes the target voltage VH*. In the I-IVtraveling mode, when a stop condition of the engine 22 is established,for example, when the requested power Pe* becomes equal to or less thana threshold for stop Pstop, the operation of the engine 22 is stoppedand transition is made to the EV traveling mode.

In the EV traveling mode, the HVECU 70 sets the requested torque Td*based on the accelerator operation amount Acc and the vehicle speed V,sets the torque command Tm1* of the motor MG1 to a value 0, and sets thetorque command Tm2* of the motor MG2 such that the requested torque Td*is output to the drive shaft 36. The target voltage VH* of the highvoltage-side power line 54 a is set based on the torque commands Tm1*,Tm2* or the rotation speeds Nm1, Nm2 of the motors MG1, MG2. Then, thetorque commands Tm1*, Tm2* of the motors MG1, MG2 or the target voltageVH* of the high voltage-side power line 54 a is transmitted to the motorECU 40. The control of the inverters 41, 42 or the boost converter 55 bythe motor ECU 40 has been described above. In the EV traveling mode,when a start condition of the engine 22 is established, for example,when the requested power Pe* calculated as in the HV traveling modebecomes equal to or less than a threshold for start Pstart greater thanthe threshold for stop Pstop, the engine 22 is started and transition ismade to the HV traveling mode.

The start of the engine 22 is performed as follows through cooperativecontrol of the HVECU 70, the engine ECU 24, and the motor ECU 40. First,torque that is the sum of cranking torque for cranking the engine 22 isoutput from the motor MG1, and cancel torque for cancelling torqueapplied to the drive shaft 36 along with the output of the crankingtorque and requested torque Td* is output from the motor MG2, therebycranking the engine 22. Then, when the rotation speed Ne of the engine22 becomes equal to or higher than a predetermined rotation speed (forexample, 500 rpm, 600 rpm, 700 rpm, or the like), the operation (fuelinjection control, ignition control, and the like) of the engine 22starts.

The control of the inverters 41, 42 will be described. In the example,the inverters 41, 42 switch (set one of first PWM control and second PWMcontrol as control for execution) and execute first PWM control andsecond PWM control. The first PWM control is control for generating afirst PWM signal of the transistors T11 to T16, T21 to T26 by comparisonof a voltage command of each phase of the motors MG1, MG2 and a carrierwave voltage (triangular wave voltage) and switching the transistors T11to T16, T21 to T26. The second PWM control is control for generating asecond PWM signal of the transistors T11 to T16, T21 to T26 based onmodulation factors Rm1, Rm2 and voltage phases θp1, θp2 of a voltage andpulse counts Np1, Np2 per unit cycle (for example, a half cycle, onecycle, or the like of the electric angle of the motors MG1, MG2) andswitching the transistors T11 to T16, T21 to T26. In the second PWMcontrol, the pulse counts Np1, Np2 are set such that a switchingfrequency of the transistors T11 to T16, T21 to T26 becomes smaller thanthat in the first PWM control. In the first PWM control, the first PWMsignal is generated at an interval Δt1 corresponding to the half cycle,one cycle, or the like of the carrier wave voltage (a triangular wavevoltage having a frequency of about 3 kHz to 5 kHz). In the second PWMcontrol, the second PWM signal is generated at an interval Δt2 longerthan the interval Δt1.

A generation method of the second PWM signal of the transistors T11 toT16 in the second PWM control of the inverter 41 will be described. Asthe generation method of the second PWM signal, for example, a firstmethod, a second method, and a third method described below can beexemplified. A generation method of the second PWM signal of thetransistors T21 to T26 in the second PWM control of the inverter 42 canbe considered as for the inverter 41.

As the first method, a method that generates the second PWM signal suchthat a low-order harmonic component is reduced more than in the firstPWM control can be exemplified. In this method, the second PWM signal ofa pulse waveform (switching pattern) having half-wave symmetry[f(ωm1·t)=−f(ωm1·t+π)] and odd symmetry [f(ωm1·t)=f(π−ωm1·t)] isgenerated in consideration of the low-order harmonic component. Here,“ωm1” is a rotational angular velocity of the motor MG1, and “t” istime. With this, it is possible to reduce loss of the motor MG1 whilereducing a low-order harmonic component. In the first method, when themotor MG1 is in a state of low rotation and low load (low torque), areduction effect of loss of the motor MG1 by suppression of a low-orderharmonic component is small. In addition, a harmonic component otherthan a target harmonic component increases due to suppression of alow-order harmonic component and iron loss of the motor increases.

As the second method, a method that the second PWM signal is generatedsuch that eddy current loss of the motor MG1 is reduced more than in thefirst PWM control can be exemplified. In this method, the second PWMsignal of a pulse waveform (switching pattern) having half-wave symmetry[f(ωm1·t)=−f(ωm1·t+π)] is generated in consideration of not only alow-order harmonic component but also a high-order harmonic component.An advantage of employing such a pulse waveform is that the range ofselection of a pulse waveform is wider than the pulse waveform used inthe first method, and improvement of controllability of both ofamplitude and phase of a frequency component included in the second PWMsignal is expected.

The pulse waveform of the second PWM signal in the second method can berepresented as Expression (1) in a case where Fourier series expansionis used. In Expression (1), “θ_(e1),m” is an m-th switching position ofthe motor MG1. “a₀” is a direct-current component. “n” is 1, 5, 7, 11,13, . . . (odd integer). “M” is a switching frequency of the transistorsT11 to T16 per unit cycle of an electric angle θ_(e1) of the motor MG1.The relationship between the switching frequency M and the pulse countNp1 becomes “M=Np1−1”. Amplitude C_(n) and phase α_(n) of each order canbe obtained using a coefficient a_(n) and a coefficient b_(n) inExpression (1) by Expression (2). In the second method, the second PWMsignal is generated using the amplitude C_(n), phase α_(n), or the likeof each order such that eddy current loss of the motor MG1 is reduced.On the other hand, iron loss W_(i) of the motor MG1 can be representedby Expression (3) as a Steinmetz experimental formula. In Expression(3), “W_(h)” is hysteresis loss of motor MG1. “W_(e)” is eddy currentloss of the motor MG1. “K_(h)” is a hysteresis loss coefficient. “B_(m)”is magnetic flux density. “f_(m1)” is a rotating magnetic flux frequencyof the motor MG1. “K_(e)” is an eddy current loss coefficient of themotor MG1. Accordingly, in the second method, in more detail, eddycurrent loss that is a high proportion in iron loss of the motor MG1 isfocused, and the second PWM signal is generated with eddy current lossas an evaluation function such that the evaluation function becomesminimum (eddy current loss in iron loss of the motor MG1 becomesminimum). With this, it is possible to further reduce loss of the motorMG1 while reducing harmonic components of low-order harmonics tohigh-order harmonics.

$\begin{matrix}{{{f\left( \theta_{e\; 1} \right)} = {\frac{a_{0}}{2} + {\sum\limits_{n = 1}^{\infty}\left( {{a_{n}\cos \; n\; \theta_{e\; 1}} + {b_{n}\sin \; n\; \theta_{e\; 1}}} \right)}}}{a_{n} = {{\frac{1}{\pi}{\int_{0}^{2\pi}{{f\left( \theta_{e\; 1} \right)}\cos \; n\; \theta_{e\; 1}d\; \theta_{e\; 1}}}} = {{- \frac{2}{n\; \pi}}{\sum\limits_{m = 1}^{M}{\left( {- 1} \right)^{m}\sin \; n\; \theta_{{e\; 1},m}}}}}}{b_{n} = {{\frac{1}{\pi}{\int_{0}^{2\pi}{{f\left( \theta_{e\; 1} \right)}\sin \; n\; \theta_{e\; 1}d\; \theta_{e\; 1}}}} = {\frac{2}{n\; \pi}\left\{ {\left( {\sum\limits_{m = 1}^{M}{\left( {- 1} \right)^{m}\cos \; n\; \theta_{{e\; 1},m}}} \right) + 1} \right\}}}}{C_{n} = \sqrt{a_{n}^{2} + b_{n}^{2}}}} & (1) \\{\alpha_{n} = {\tan^{- 1}\frac{b_{n}}{a_{n}}}} & (2) \\{W_{i} = {{W_{h} + W_{e}} = {{K_{h}B_{m}^{2}f_{m\; 1}} + {K_{e}B_{m}^{2}f_{m\; 1}}}}} & (3)\end{matrix}$

As the third method, a method that generates the second PWM signal suchthat total loss Lsum1 of loss Lmg1 of the motor MG1 and loss Linv1 ofthe inverter 41 is reduced can be exemplified. FIG. 3 is an explanatoryview showing an example of the relationship between the pulse count Np1in the first PWM control and the second PWM control and the total lossLsum1 of the loss Lmg1 of the motor MG1 and the loss Linv1 of theinverter 41. In the drawing, a point A is the pulse count Np1 where thetotal loss Lsum1 in the first PWM control becomes minimum, and a point Bis the pulse count Np1 where the total loss Lsum1 in the second PWMcontrol becomes minimum. The inventors have found from an experiment oran analysis that, in order to further reduce the total loss Lsum1compared to the first method or the second method, as shown in FIG. 3,the pulse count Np1 should be used such that the switching frequency ofthe transistors TI to T16 of the inverter 41 becomes smaller than thatin the first PWM control. Accordingly, in the third method, the secondPWM signal is generated such that harmonic components of low-orderharmonics to high-order harmonics are reduced and the total loss Lsum1is reduced compared to the first PWM control using the pulse count Np1defined in this manner. With this, it is possible to further reduce thetotal loss Lsum1 while reducing harmonic components of low-orderharmonics to high-order harmonics.

In the example, as the generation method of the second PWM signal of thetransistors T11 to T16 in the second PWM control of the inverter 41, thethird method among the first method, the second method, and the thirdmethod described above is used. The first method or the second methodmay be used.

In a case of executing the first PWM control, the switching frequency ofthe transistors T11 to T16, T21 to T26 increases and a generation cycleof a PWM signal is shortened compared to a case of executing the secondPWM control. For this reason, it is possible to suppress an increase innoise (electromagnetic noise) due to switching of the transistors T21 toT26 or to enhance the controllability of the motors MG1, MG2. In a caseof executing the second PWM control, electromagnetic noise is likely toincrease or the controllability of the motors MG1, MG2 is likely to bedegraded compared to a case of executing the first PWM control; however,it is possible to further reduce the total loss Lsum1 while reducingharmonic components of low-order harmonics to high-order harmonics.

Next, the operation of the hybrid vehicle 20 of the example configuredas above, and in particular, an operation in a case of setting thecontrol for execution of the inverters 41, 42 from the first PWM controlor the second PWM control will be described. FIG. 4 is a flowchartshowing an example of a control-for-execution setting routine that isexecuted by the motor ECU 40. This routine is repeatedly executed.

In a case where the control-for-execution setting routine is executed,the motor ECU 40 first inputs data, such as permission flags F1, F2, atarget operation point (rotation speed Nm1 and torque command Tm1*) P1of the motor MG1, and a target operation point (rotation speed Nm2 andtorque command Tm2*) P2 of the motor MG2, as input (Step S100). Thepermission flags F1, F2 are flags that are set to a value of 1 when theexecution of the second PWM control as control of the inverters 41, 42is permitted and are set to a value of 0 when the execution of thesecond PWM control as the control of the inverters 41, 42 is inhibited.The flags set through a permission flag setting routine FIG. 6 that isrepeatedly executed in parallel with this routine are input. As therotation speeds Nm1, Nm2 of the motors MG1, MG2, values calculated basedon the rotation positions θm1, θm2 of the rotors of the motors MG1, MG2from the rotation position detection sensors 43, 44 are input. As thetorque commands Tm1*, Tm2* of the motors MG1, MG2, the values setthrough the above-described drive control are input.

In a case where data is input in this manner, the value of the inputpermission flag F1 is examined (Step S110), and determination is madewhether the target operation point P1 of the motor MG1 belongs to anarea of the first PWM control or an area of the second PWM control (StepS120). FIG. 5 is an explanatory view showing an example of therelationship between the target operation point P1 of the motor MG1, andthe area of the first PWM control and the area of the second PWMcontrol. In the example, in regards to the area of the first PWM controland the area of the second PWM control for the target operation point P1of the motor MG1, an area where an effect of the execution of the secondPWM control is expected to some extent based on an experiment result oran analysis result of the execution of the first PWM control or thesecond PWM control on each target operation point P1 of the motor MG1 isdefined as an area of the second PWM control. An area where the effectis not much expected is defined as an area of the first PWM control. Inthe example of FIG. 5, for the target operation point P1 of the motorMG1, the following areas 1 to 5 are set as the area of the second PWMcontrol, and an area other than the area of the second PWM control isset as the area of the first PWM control. As the area 1, an area wherethe rotation speed Nm1 of the motor MG1 is 1000 rpm to 3500 rpm and thetorque command Tm1* is equal to or greater than 10 Nm and an area wherethe rotation speed Nm1 is 1000 rpm to 3500 rpm and the torque commandTm1* is −100 Nm to −10 Nm are set. As the area 2, an area where therotation speed Nm1 of the motor MG1 is 3500 rpm to 6000 rpm and thetorque command Tm1* is 10 Nm to 150 Nm and an area where the rotationspeed Nm1 is 3500 rpm to 6000 rpm and the torque command Tm1* is −100 Nmto −10 Nm are set. As the area 3, an area where the rotation speed Nm1of the motor MG1 is 3500 rpm to 6000 rpm and the torque command Tm1* isequal to or greater than 150 Nm is set. As the area 4, an area where therotation speed Nm1 of the motor MG1 is 6000 rpm to 9000 rpm and thetorque command Tm1* is 10 Nm to 100 Nm and an area where the rotationspeed Nm1 is 6000 rpm to 9000 rpm and the torque command Tm1* is −50 Nmto −10 Nm are set. As the area 5, an area where the rotation speed Nm1of the motor MG1 is 6000 rpm to 9000 rpm and the torque command Tm1* is100 Nm to 150 Nm and an area where the rotation speed Nm1 is 6000 rpm to9000 rpm and the torque command Tm1* is −100 Nm to −50 Nm are set. InFIG. 5, the values of the rotation speed Nm1 of the motor MG1 or thetorque command Tm1*, division between the area of the first PWM controland the area of the second PWM control, and division between the areasin the area of the second PWM control (including the number of areas)are merely illustrative, and may be appropriately set according to thespecifications of the motor MG1, the inverter 41, and the like.

In Step S110, when the permission flag F1 is the value of 1, that is,when the execution of the second PWM control as the control of theinverter 41 is permitted, and in Step S120, when the target operationpoint P1 of the motor MG1 belongs to the area of the second PWM control,the second PWM control is set as the control for execution of theinverter 41 (Step S130). In Step S110, when the permission flag F1 isthe value of 0, that is, when the execution of the second PWM control asthe control of the inverter 41 is inhibited, or in Step S110, when thepermission flag F1 is the value of 1, that is, when the execution of thesecond PWM control as the control of the inverter 41 is permitted, andin Step S120, when the target operation point P1 of the motor MG1belongs to the area of the first PWM control, the first PWM control isset as the control for execution of the inverter 41 (Step S140).

Next, the value of the permission flag F2 is examined (Step S150), anddetermination is made whether the target operation point P2 of the motorMG2 belongs to the area of the first PWM control or the area of thesecond PWM control (Step S160). The area of the first PWM control andthe area of the second PWM control for the target operation point P2 ofthe motor MG2 are set in the same manner as the area of the first PWMcontrol and the area of the second PWM control for the target operationpoint P1 of the motor MG1.

In Step S150, when the permission flag F2 is the value of 1, that is,when the execution of the second PWM control as the control of theinverter 42 is permitted, and in Step S160, when the target operationpoint P2 of the motor MG2 belongs to the area of the second PWM control,the second PWM control is set as the control for execution of theinverter 42 (Step S170), and this routine ends. In Step S150, when thepermission flag F2 is the value of 0, that is, when the execution of thesecond PWM control as the control of the inverter 42 is inhibited, or inStep S150, when the permission flag F2 is the value of 1, that is, whenthe execution of the second PWM control as the control of the inverter42 is permitted, and in Step S160, when the target operation point P2 ofthe motor MG2 belongs to the area of the first PWM control, the firstPWM control is set as the control for execution of the inverter 42 (StepS180), and this routine ends.

Next, a permission flag setting routine of FIG. 6 will be described.This routine is repeatedly executed in parallel with thecontrol-for-execution setting routine of FIG. 4 by the motor ECU 40. Ina case where the permission flag setting routine is executed, the motorECU 40 first determines whether or not zero learning of the rotationposition detection sensor 43 that detects the rotation position θm1 ofthe rotor of the motor MG1 or the current sensors 45 u, 45 v that detectthe phase currents Iu1, Iv1 flowing in the motor MG1 is completed (StepS200).

In regard to the zero learning (learning of an offset amount) of therotation position detection sensor 43, current commands of d-axis andq-axis are set as a value of 0 during the rotation of the motor MG1, andthe offset amount of the rotation position θm1 of the rotor of the motorMG1 from the rotation position detection sensor 43 is adjusted such thata voltage command of d-axis at this time becomes a value of 0. The zerolearning can be performed by storing the adjusted offset amount in theRAM (not shown), a flash memory, or the like. The zero learning(learning of an offset amount) of the current sensors 45 u, 45 v can beperformed, for example, by storing the offset amounts of the phasecurrents Iu1, Iv1 of the motor MG1 current sensors 45 u, 45 v when themotor MG1 is stopped (a current does not flow in the three-phase coilsof the motor MG1) in the RAM (not shown), a flash memory, or the like.The zero learning of the rotation position detection sensor 43 or thecurrent sensors 45 u, 45 v can be performed in a frequency of, forexample, once in one trip or several trips. Alternatively, the zerolearning may be performed in a trip immediately after the rotationposition detection sensor 43 or the current sensors 45 u, 45 v arereplaced.

The processing of Step S200 can be performed, for example, by readinginformation regarding determination of the presence or absence of thezero learning of the rotation position detection sensor 43 or thecurrent sensors 45 u, 45 v through a routine (not shown) and written inthe RAM (not shown). The processing of Step S200 is processing fordetermining whether or not the high controllability of the motor MG1 isrequested. When the zero learning of the rotation position detectionsensor 43 or the current sensors 45 u, 45 v is not completed, there is apossibility that the rotation position θm1 of the rotor of the motor MG1from the rotation position detection sensor 43 or the phase currentsIu1, Iv1 of the motor MG1 from the current sensors 45 u, 45 v are notcorrect values, and there is a possibility that the controllability ofthe motor MG1 is further degraded. Accordingly, in the example,determination is made whether or not the zero learning of the rotationposition detection sensor 43 or the current sensors 45 u, 45 v iscompleted, thereby determining whether or not the high controllabilityof the motor MG1 is requested.

In Step S200, when the zero learning of the rotation position detectionsensor 43 and the current sensors 45 u, 45 v is completed, determinationis made that the high controllability of the motor MG1 is not requested(is secured in a needed level), and the value of 1 is set as thepermission flag F1. That is, the execution of the second PWM control asthe control of the inverter 41 is permitted (Step S210). In this case,in the control-for-execution setting routine of FIG. 4, the first PWMcontrol or the second PWM control is set as the control for execution ofthe inverter 41 according to the target operation point P1 of the motorMG1.

When the zero learning of at least one of the rotation positiondetection sensor 43 and the current sensors 45 u, 45 v is not completed,determination is made that the high controllability of the motor MG1 isrequested (there is a possibility that the controllability of the motorMG1 is further degraded), and the value of 0 is set as the permissionflag F1. That is, the execution of the second PWM control as the controlof the inverter 41 is inhibited (Step S220). In this case, in thecontrol-for-execution setting routine of FIG. 4, the first PWM controlis set as the control for execution of the inverter 41 regardless of thetarget operation point P1 of the motor MG1.

In a case where the permission flag F1 is set in this manner,subsequently, determination is made whether or not zero learning of therotation position detection sensor 44 that detects the rotation positionθm2 of the rotor of the motor MG2 or the current sensors 46 u, 46 v thatdetect the phase currents Iu2, Iv2 flowing in the motor MG2 is completed(Step S230). The zero learning (learning of an offset amount) of therotation position detection sensor 44 or the current sensors 46 u, 46 vcan be performed in the same manner as the zero learning of the rotationposition detection sensor 43 or the current sensors 45 u, 45 v. Theprocessing of Step S230 can be performed (determined) in the same manneras the processing of Step S200, except that the processing of Step S230is processing for determining whether or not the high controllability ofthe motor MG2, not the motor MG1, is requested.

In Step S230, when the zero learning of the rotation position detectionsensor 44 and the current sensors 46 u, 46 v is completed, determinationis made that the high controllability of the motor MG2 is not requested(is secured in a needed level), and the value of 1 is set as thepermission flag F2. That is, the execution of the second PWM control asthe control of the inverter 42 is permitted (Step S240), and thisroutine ends. In this case, in the control-for-execution setting routineof FIG. 4, the first PWM control or the second PWM control is set as thecontrol for execution of the inverter 42 according to the targetoperation point P2 of the motor MG2.

When the zero learning of at least one of the rotation positiondetection sensor 44 and the current sensors 46 u, 46 v is not completed,determination is made that the high controllability of the motor MG2 isrequested (there is a possibility that the controllability of the motorMG2 is further degraded), and the value of 0 is set as the permissionflag F2. That is, the execution of the second PWM control as the controlof the inverter 42 is inhibited (Step S250), and this routine ends. Inthis case, in the control-for-execution setting routine of FIG. 4, thefirst PWM control is set as the control for execution of the inverter 42regardless of the target operation point P2 of the motor MG2.

As described above, in a case of executing the second PWM control as thecontrol of the inverter 41, the controllability of the motor MG1 islikely to be degraded compared to a case of executing the first PWMcontrol. For this reason, in a case where the second PWM control isexecuted as the control of the inverter 41 when the zero learning of atleast one of the rotation position detection sensor 43 and the currentsensors 45 u, 45 v is not completed, there is a possibility that thecontrollability of the motor MG1 is further degraded and an overcurrentor an overvoltage occurs in the inverter 41. In the example, when thezero learning of at least one of the rotation position detection sensor43 and the current sensors 45 u, 45 v is not completed, determination ismade that the high controllability of the motor MG1 is requested (thereis a possibility that the controllability of the motor MG1 is furtherdegraded), and as the control of the inverter 41, the execution of thesecond PWM control is inhibited and the first PWM control is executed.With this, it is possible to more sufficiently satisfy a request for thehigh controllability of the motor MG1. Specifically, it is possible tosuppress the occurrence of an overcurrent or an overvoltage in theinverter 41. The control of the inverter 42 can be considered similarly.

In the hybrid vehicle 20 of the example described above, when the zerolearning of at least one of the rotation position detection sensor 43and the current sensors 45 u, 45 v is not completed, determination ismade that the high controllability of the motor MG1 is requested, and asthe control of the inverter 41, the execution of the second PWM controlis inhibited and the first PWM control is executed. Similarly, when thezero learning of at least one of the rotation position detection sensor44 and the current sensors 46 u, 46 v is not completed, determination ismade that the high controllability of the motor MG2 is requested, and asthe control of the inverter 42, the execution of the second PWM controlis inhibited and the first PWM control is executed. With this, it ispossible to more sufficiently satisfy a request for the highcontrollability of the motors MG1, MG2.

In the hybrid vehicle 20 of the example, although the motor ECU 40 setsthe permission flag F through the permission flag setting routine ofFIG. 6, the motor ECU 40 may set the permission flag F through any oneof permission flag setting routines of FIGS. 7 to 12. Hereinafter, thepermission flag setting routines will be described in order.

First, the permission flag setting routine of FIG. 7 will be described.In a case where the permission flag setting routine of FIG. 7 isexecuted, the motor ECU 40 first determines whether or not anabnormality occurs in the rotation position detection sensor 43 thatdetects the rotation position θm1 of the rotor of the motor MG1 or thecurrent sensors 45 u, 45 v that detect the phase currents Iu1, Iv1flowing in the motor MG1 (Step S300). The processing of Step S300 can beperformed, for example, by reading information regarding determinationof the presence or absence of an abnormality in the rotation positiondetection sensor 43 or the current sensors 45 u, 45 v through a routine(not shown) and written in the RAM (not shown). Similarly to theprocessing of Step S200 of the permission flag setting routine of FIG.6, the processing of Step S300 is processing for determining whether ornot the high controllability of the motor MG1 is requested. When anabnormality occurs in the rotation position detection sensor 43 or thecurrent sensors 45 u, 45 v, there is a possibility that the rotationposition θm1 of the rotor of the motor MG1 from the rotation positiondetection sensor 43 of the phase currents Iu1, Iv1 of the motor MG1 fromthe current sensors 45 u, 45 v are not correct value or are not input,and there is a possibility that the controllability of the motor MG1 isfurther degraded. Accordingly, in this modification example,determination is made whether or not an abnormality occurs in therotation position detection sensor 43 or the current sensors 45 u, 45 v,thereby determining whether or not the high controllability of the motorMG1 is requested.

In Step S300, when an abnormality does not occur in both of the rotationposition detection sensor 43 and the current sensors 45 u, 45 v,determination is made that the high controllability of the motor MG1 isnot requested (is secured in a needed level), and the value of 1 is setas the permission flag F1. That is, the execution of the second PWMcontrol as the control of the inverter 41 is permitted (Step S310). Whenan abnormality occurs in at least one of the rotation position detectionsensor 43 and the current sensors 45 u, 45 v, determination is made thatthe high controllability of the motor MG1 is requested (there is apossibility that the controllability of the motor MG1 is furtherdegraded), and the value of 0 is set as the permission flag F1. That is,the execution of the second PWM control as the control of the inverter41 is inhibited (Step S320).

In a case where the permission flag F1 is set in this manner,subsequently, determination is made whether or not an abnormality occursin the rotation position detection sensor 44 that detects the rotationposition θm2 of the rotor of the motor MG2 or the current sensors 46 u,46 v that detect the phase currents Iu2, Iv2 flowing in the motor MG2(Step S330). The processing of Step S330 can be performed (determined)in the same manner as the processing of Step S300, except that theprocessing of Step S330 is processing for determining whether or not thehigh controllability of the motor MG2, not the motor MG1, is requested.

In Step S330, when an abnormality does not occur in both of the rotationposition detection sensor 44 and the current sensors 46 u, 46 v,determination is made that the high controllability of the motor MG2 isnot requested (is secured in a needed level), and the value of 1 is setas the permission flag F2. That is, the execution of the second PWMcontrol as the control of the inverter 42 is permitted (Step S340), andthis routine ends. When an abnormality occurs in at least one of therotation position detection sensor 44 and the current sensors 46 u, 46v, determination is made that the high controllability of the motor MG2is requested (there is a possibility that the controllability of themotor MG2 is further degraded), and the value of 0 is set as thepermission flag F2. That is, the execution of the second PWM control asthe control of the inverter 42 is inhibited (Step S350), and thisroutine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverter 41, the controllability of the motor MG1 islikely to be degraded compared to a case of executing the first PWMcontrol. For this reason, in a case where the second PWM control isexecuted as the control of the inverter 41 when an abnormality occurs inat least one of the rotation position detection sensor 43 and thecurrent sensors 45 u, 45 v, there is a possibility that thecontrollability of the motor MG1 is further degraded and an overcurrentor an overvoltage occurs in the inverter 41. In this modificationexample, when an abnormality occurs in at least one of the rotationposition detection sensor 43 and the current sensors 45 u, 45 v,determination is made that the high controllability of the motor MG1 isrequested (there is a possibility that the controllability of the motorMG1 is further degraded), and as the control of the inverter 41, theexecution of the second PWM control is inhibited and the first PWMcontrol is executed. With this, it is possible to more sufficientlysatisfy a request for the high controllability of the motor MG1.Specifically, it is possible to suppress the occurrence of anovercurrent or an overvoltage in the inverter 41. The control of theinverter 42 can be considered similarly.

Next, the permission flag setting routine of FIG. 8 will be described.In a case where the permission flag setting routine of FIG. 8 isexecuted, the motor ECU 40 first inputs data, such as torque commandchange rates ΔTm1*, ΔTm2* or rotation speed change rates ΔNm1, ΔNm2 ofthe motors MG1, MG2, a voltage change rate ΔVH of the high voltage-sidepower line 54 a, and a voltage change rate ΔVb of the battery 50 (StepS400). The torque command change rates ΔTm1*, ΔTm2* of the motors MG1,MG2 are the amounts of change per unit time of the torque commands Tm1*,Tm2* of the motors MG1, MG2. The rotation speed change rates ΔNm1, ΔNm2of the motors MG1, MG2 are the amounts of change per unit time of therotation speeds Nm1, Nm2 of the motors MG1, MG2. The voltage change rateΔVH of the high voltage-side power line 54 a is the amount of change perunit time of the voltage VH of the high voltage-side power line 54 a.The voltage change rate ΔVb of the battery 50 is the amount of changeper unit time of the voltage Vb of the battery 50.

In a case where data is input in this manner, determination is madewhether or not a drive state of the motor MG1 is rapidly changed (StepsS410 to S416). Specifically, an absolute value of the torque commandchange rate ΔTm1* of the motor MG1 is compared with a threshold ΔTm1ref,thereby determining whether or not the torque command Tm1* of the motorMG1 is rapidly changed (Step S410). An absolute value of the rotationspeed change rate ΔNm1 of the motor MG1 is compared with a thresholdΔNm1ref, thereby determining whether or not the rotation speed Nm1 ofthe motor MG1 is rapidly changed (Step S412). An absolute value of thevoltage change rate ΔVH of the high voltage-side power line 54 a iscompared with a threshold ΔVHref, thereby determining whether or not thevoltage VH of the high voltage-side power line 54 a is rapidly changed(Step S414). An absolute value of the voltage change rate ΔVb of thebattery 50 is compared with a threshold ΔVbref, thereby determiningwhether or not the voltage Vb of the battery 50 is rapidly changed (StepS416).

Similarly to the processing of Step S200 of the permission flag settingroutine of FIG. 6, the processing of Steps S410 to S416 is processingfor determining whether or not the high controllability of the motor MG1is requested. When the drive state of the motor MG1 is rapidly changed,there is a possibility that the controllability of the motor MG1 isfurther degraded. Accordingly, in this modification example,determination is made whether or not the drive state of the motor MG1 israpidly changed, thereby determining whether or not the highcontrollability of the motor MG1 is requested. The thresholds ΔTm1ref,ΔNm1ref, ΔVHref, ΔVbref can be appropriately set based on thespecifications of the motor MG1, the inverter 41, the high voltage-sidepower line 54 a, and the battery 50, or the like.

In Steps S410 to S416, when the absolute value of the torque commandchange rate ΔTm1* is equal to or less than the threshold ΔTm1ref, theabsolute value of the rotation speed change rate ΔNm1 is equal to orless than the threshold ΔNm ref, the absolute value of the voltagechange rate ΔVH is equal to or less than the threshold ΔVHref, and theabsolute value of the voltage change rate ΔVb is equal to or less thanthe threshold ΔVbref, that is, when the drive state of the motor MG1 isnot rapidly changed, determination is made that the high controllabilityof the motor MG1 is not requested (is secured in a needed level), andthe value of 1 is set as the permission flag F1. That is, the executionof the second PWM control as the control of the inverter 41 is permitted(Step S420).

When the absolute value of the torque command change rate ΔTm1* isgreater than the threshold ΔTm1ref, when the absolute value of therotation speed change rate ΔNm1 is greater than the threshold ΔNm1ref,when the absolute value of the voltage change rate ΔVH is greater thanthe threshold ΔVHref, or when the absolute value of the voltage changerate ΔVb is greater than the threshold ΔVbref, that is, when the drivestate of the motor MG1 is rapidly changed, the determination is madethat the high controllability of the motor MG1 is requested (there is apossibility that the controllability of the motor MG1 is furtherdegraded), and the value of 0 is set as the permission flag F1. That is,the execution of the second PWM control as the control of the inverter41 is inhibited (Step S430).

In a case where the permission flag F1 is set in this manner,subsequently, determination is made whether or not the drive state ofthe motor MG2 is rapidly changed (Steps S440 to S446). Specifically, anabsolute value of the torque command change rate ΔTm2* of the motor MG2is compared with a threshold ΔTm2ref, thereby determining whether or notthe torque command Tm2* of the motor MG2 is rapidly changed (Step S440).An absolute value of the rotation speed change rate ΔNm2 of the motorMG2 is compared with a threshold ΔNm2ref, thereby determining whether ornot the rotation speed Nm2 of the motor MG2 is rapidly changed (StepS442). An absolute value of the voltage change rate ΔVH of the highvoltage-side power line 54 a is compared with a threshold ΔVHref,thereby determining whether or not the voltage VH of the highvoltage-side power line 54 a is rapidly changed (Step S444). An absolutevalue of the voltage change rate ΔVb of the battery 50 is compared witha threshold ΔVbref, thereby determining whether or not the voltage Vb ofthe battery 50 is rapidly changed (Step S446). The processing of StepsS440 to S446 can be performed (determined) in the same manner as theprocessing of Steps S410 to S416, except that the processing of StepsS440 to S446 is processing for determining whether or not the highcontrollability of the motor MG2, not the motor MG1, is requested.

In Steps S440 to S446, when the absolute value of the torque commandchange rate ΔTm2* is equal to or less than the threshold ΔTm2ref, theabsolute value of the rotation speed change rate ΔNm2 is equal to orless than the threshold ΔNm2ref, the absolute value of the voltagechange rate ΔVH is equal to or less than the threshold ΔVHref, and theabsolute value of the voltage change rate ΔVb is equal to or less thanthe threshold ΔVbref, that is, when the drive state of the motor MG2 isnot rapidly changed, determination is made that the high controllabilityof the motor MG2 is not requested (is secured in a needed level), andthe value of 1 is set as the permission flag F2. That is, the executionof the second PWM control as the control of the inverter 42 is permitted(Step S450), and this routine ends.

When the absolute value of the torque command change rate ΔTm2* isgreater than the threshold ΔTm2ref, when the absolute value of therotation speed change rate ΔNm2 is greater than the threshold ΔNm2ref,when the absolute value of the voltage change rate ΔVH is greater thanthe threshold ΔVHref, or when the absolute value of the voltage changerate ΔVb is greater than the threshold ΔVbref, that is, when the drivestate of the motor MG2 is rapidly changed, determination is made thatthe high controllability of the motor MG2 is requested (there is apossibility that the controllability of the motor MG2 is furtherdegraded), the value of 0 is set as the permission flag F2. That is, theexecution of the second PWM control as the control of the inverter 42 isinhibited (Step S460), and this routine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverter 41, the controllability of the motor MG1 islikely to be degraded compared to a case of executing the first PWMcontrol. For this reason, in a case where the second PWM control isexecuted as the control of the inverter 41 when the drive state of themotor MG1 is rapidly changed, there is a possibility that thecontrollability of the motor MG1 is further degraded and an overcurrentor an overvoltage occurs in the inverter 41. In this modificationexample, when the drive state of the motor MG1 is rapidly changed,determination is made that the high controllability of the motor MG1 isrequested (there is a possibility that the controllability of the motorMG1 is further degraded), and as the control of the inverter 41, theexecution of the second PWM control is inhibited and the first PWMcontrol is executed. With this, it is possible to more sufficientlysatisfy a request for the high controllability of the motor MG1.Specifically, it is possible to suppress the occurrence of anovercurrent or an overvoltage in the inverter 41. The control of theinverter 42 can be considered similarly.

Next, the permission flag setting routine of FIG. 9 will be described.In a case where the permission flag setting routine of FIG. 9 isexecuted, the motor ECU 40 first determines whether or not vibrationdamping control by the motor MG1 is performed (Step S500). The vibrationdamping control by the motor MG1 is performed, for example, when theengine 22 is started (when the engine 22 is started by cranking theengine 22 with the motor MG1), when fluctuation of rotation of theengine 22 is comparatively large during the operation of the engine 22,or the like. The processing of Step S500 can be performed by readinginformation regarding determination whether or not the vibration dampingcontrol by the motor MG1 is performed through a routine (not shown) andwritten in the RAM (not shown). Similarly to the processing of Step S200of the permission flag setting routine of FIG. 6, the processing of StepS500 is processing for determining whether or not the highcontrollability of the motor MG1 is requested. When the vibrationdamping control by the motor MG1 is performed, in order to sufficientlyexhibit vibration damping performance, the controllability of the motorMG1 may be further enhanced (is requested to be further enhanced).Accordingly, in this modification example, determination is made whetheror not the vibration damping control by the motor MG1 is performed,thereby determining whether or not the high controllability of the motorMG1 is requested.

In Step S500, when the vibration damping control by the motor MG1 is notperformed, determination is made that the high controllability of themotor MG1 is not requested (the controllability of the motor MG1 is notrequested to be further enhanced), and the value of 1 is set as thepermission flag F1. That is, the execution of the second PWM control asthe control of the inverter 41 is permitted (Step S510). When thevibration damping control by the motor MG1 is performed, determinationis made that the high controllability of the motor MG1 is requested (thecontrollability of the motor MG1 is requested to be further enhanced),and the value of 0 is set as the permission flag F1. That is, theexecution of the second PWM control as the control of the inverter 41 isinhibited (Step S520).

In a case where the permission flag F1 is set in this manner,subsequently, determination is made whether or not vibration dampingcontrol by the motor MG2 is performed (Step S530). The vibration dampingcontrol by the motor MG2 is performed when the engine 22 is started,when fluctuation of rotation of the drive wheels 39 a, 39 b (drive shaft36) is comparatively large, or the like. The processing of Step S530 canbe performed (determined) in the same manner as the processing of StepS500, except that the processing of Step S530 is processing fordetermining whether or not the high controllability of the motor MG2,not the motor MG1, is requested.

In Step S530, when the vibration damping control by the motor MG2 is notperformed, determination is made that the high controllability of themotor MG2 is not requested (the controllability of the motor MG2 is notrequested to be further enhanced), and the value of 1 is set as thepermission flag F2. That is, the execution of the second PWM control asthe control of the inverter 42 is permitted (Step S540), and thisroutine ends. When the vibration damping control by the motor MG2 isperformed, determination is made that the high controllability of themotor MG2 is requested (the controllability of the motor MG2 isrequested to be further enhanced), and the value of 0 is set as thepermission flag F2. That is, the execution of the second PWM control asthe control of the inverter 42 is inhibited (Step S550), and thisroutine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverter 41, the controllability of the motor MG1 islikely to be degraded compared to a case of executing the first PWMcontrol. For this reason, in a case where the second PWM control isexecuted as the control of the inverter 41 when the vibration dampingcontrol of the motor MG1 is performed, there is a possibility that it isnot possible to sufficiently exhibit the vibration damping performance.In this modification example, when the vibration damping control of themotor MG1 is performed, determination is made that the highcontrollability of the motor MG1 is requested (the controllability ofthe motor MG1 is requested to be further enhanced), and as the controlof the inverter 41, the execution of the second PWM control is inhibitedand the execution of the first PWM control is performed. With this, itis possible to more sufficiently satisfy a request for the highcontrollability of the motor MG1. Specifically, it is possible tosufficiently exhibit the vibration damping performance. The control ofthe inverter 42 can be considered similarly.

Next, the permission flag setting routine of FIG. 10 will be described.In a case where the permission flag setting routine of FIG. 10 isexecuted, the motor ECU 40 first determines whether or not anabnormality occurs in the current sensor 55 a that detects the currentIL flowing in the reactor L or the voltage sensor 57 a that detects thevoltage VH of the high voltage-side power line 54 a (capacitor 57) (StepS600). The processing of Step S600 can be performed by readinginformation regarding determination of the presence or absence of anabnormality in the current sensor 55 a or the voltage sensor 57 athrough a routine (not shown) and written in the RAM (not shown). Theprocessing of Step S600 is processing for determining whether or not thehigh controllability of the motors MG1, MG2 is requested. When anabnormality occurs in the current sensor 55 a or the voltage sensor 57a, there is a possibility that the current IL of the reactor L from thecurrent sensor 55 a or the voltage VH of the high voltage-side powerline 54 a from the voltage sensor 57 a is not a correct value or is notinput, and there is a possibility that the controllability of the motorsMG1, MG2 is further degraded. Accordingly, in this modification example,determination is made whether or not an abnormality occurs in thecurrent sensor 55 a or the voltage sensor 57 a, thereby determiningwhether or not the high controllability of the motors MG1, MG2 isrequested.

In Step S600, when an abnormality does not occur in both of the currentsensor 55 a and the voltage sensor 57 a, determination is made that thehigh controllability of the motors MG1, MG2 is not requested (is securedin a needed level), and the value of 1 is set as the permission flagsF1, F2. That is, the execution of the second PWM control as the controlof the inverters 41, 42 is permitted (Step S610), and this routine ends.When an abnormality occurs in at least one of the current sensor 55 aand the voltage sensor 57 a, determination is made that the highcontrollability of the motors MG1, MG2 is requested (there is apossibility that the controllability of the motors MG1, MG2 is furtherdegraded), and the value of 0 is set as the permission flags F1, F2.That is, the execution of the second PWM control as the control of theinverters 41, 42 is inhibited (Step S620), and this routine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverters 41, 42, the controllability of the motors MG,MG2 is likely to be degraded compared to a case of executing the firstPWM control. For this reason, in a case where the second PWM control isexecuted as the control of the inverters 41, 42 when an abnormalityoccurs in at least one of the current sensor 55 a and the voltage sensor57 a, there is a possibility that the controllability of the motors MG1,MG2 is further degraded and an overcurrent or an overvoltage occurs inthe inverters 41, 42. In this modification example, when an abnormalityoccurs in at least one of the current sensor 55 a and the voltage sensor57 a, determination is made that the high controllability of the motorsMG1, MG2 is requested (there is a possibility that the controllabilityof the motors MG1, MG2 is further degraded), and as the control of theinverters 41, 42, the execution of the second PWM control is inhibitedand the first PWM control is executed. With this, it is possible to moresufficiently satisfy a request for the high controllability of themotors MG1, MG2. Specifically, it is possible to suppress the occurrenceof an overcurrent or an overvoltage in the inverters 41, 42.

Next, the permission flag setting routine of FIG. 11 will be described.In a case where the permission flag setting routine of FIG. 11 isexecuted, the motor ECU 40 determines whether or not a battery-lesstraveling mode is executed (Step S700). The battery-less traveling modeis a mode in which the system main relay 56 is turned off (the battery50 is disconnected from the boost converter 55 side), the drive of theboost converter 55 is stopped, and traveling is performed with the driveof the engine 22 and the motors MG1, MG2. As a case where traveling isperformed in the battery-less traveling mode, a case where anabnormality occurs in the battery 50, or the like can be exemplified. Inthe battery-less traveling mode, the HVECU 70 sets the requested torqueTd* based on the accelerator operation amount Acc and the vehicle speedV. A rotation speed Ne1 is set as the target rotation speed Ne* of theengine 22. A voltage VH1 is set as the target voltage VH* of the highvoltage-side power line 54 a. The torque commands Tm1*, Tm2* of themotors MG1, MG2 are set such that the voltage VH of the highvoltage-side power line 54 a becomes the target voltage VH* and therequested torque Td* is output to the drive shaft 36. As the rotationspeed Ne1, a rotation speed that enables efficient operation of theengine 22, or the like can be used. As the voltage VH1, a voltage thatis slightly lower than an allowable upper limit voltage of the highvoltage-side power line 54 a (capacitor 57), or the like can be used.Then, the target rotation speed Ne* of the engine 22 is transmitted tothe engine ECU 24, and the torque commands Tm1*, Tm2* of the motors MG1,MG2 are transmitted to the motor ECU 40. The engine ECU 24 performs theintake air amount control, the fuel injection control, the ignitioncontrol, and the like of the engine 22 such that the engine 22 rotatesat the target rotation speed Ne*. The motor ECU 40 performs theswitching control of the transistors T11 to T16, T21 to T26 of theinverters 41, 42 such that the motors MG1, MG2 are driven with thetorque commands Tm1*, Tm2*.

The processing of Step S700 can be performed, for example, by readinginformation regarding determination of whether or not the battery-lesstraveling mode is executed through a routine (not shown) and written inthe RAM (not shown). The processing of Step S700 is processing fordetermining whether or not the high controllability of the motors MG1,MG2 is requested. In a case of traveling in the battery-less travelingmode, since fluctuation of the sum of the electric power consumption ofthe motors MG1, MG2 cannot be absorbed with the battery 50, the sum ofthe electric power consumption (generated electric power) of the motorsMG1, MG2 needs to be adjusted with higher accuracy compared to a case oftraveling with the system main relay 56 being turned on, and thecontrollability of the motors MG1, MG2 needs to be further enhanced (isrequested to be further enhanced). Accordingly, in this modificationexample, determination is made whether or not the battery-less travelingmode is executed, thereby determining whether or not the highcontrollability of the motors MG1, MG2 is requested.

In Step S700, when the battery-less traveling mode is not executed,determination is made that the high controllability of the motors MG1,MG2 is not requested (the controllability of the motors MG1, MG2 is notrequested to be further enhanced), and the value of 1 is set as thepermission flags F1, F2. That is, the execution of the second PWMcontrol as the control of the inverters 41, 42 is permitted (Step S710),and this routine ends. When the battery-less traveling mode is executed,determination is made that the high controllability of the motors MG1,MG2 is requested (the controllability of the motors MG1, MG2 isrequested to be further enhanced), and the value of 0 is set as thepermission flags F1, F2. That is, the execution of the second PWMcontrol as the control of the inverters 41, 42 is inhibited (Step S720),and this routine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverters 41, 42, the controllability of the motors MG,MG2 is likely to be degraded compared to a case of executing the firstPWM control. For this reason, in a case where the second PWM control isexecuted as the control of the inverters 41, 42 when the battery-lesstraveling mode is executed, there is a possibility that it is notpossible to adjust the sum of the electric power consumption (generatedelectric power) of the motors MG1, MG2 with higher accuracy. In thismodification example, when the battery-less traveling mode is executed,determination is made that the high controllability of the motors MG1,MG2 is requested (the controllability of the motors MG1, MG2 isrequested to be further enhanced), and as the control of the inverters41, 42, the execution of the second PWM control is inhibited and thefirst PWM control is executed. With this, it is possible to moresufficiently satisfy a request for the high controllability of themotors MG1, MG2. Specifically, it is possible to adjust the sum of theelectric power consumption (generated electric power) of the motors MG1,MG2 with higher accuracy.

Next, the permission flag setting routine of FIG. 12 will be described.In a case where the permission flag setting routine of FIG. 12 isexecuted, the motor ECU 40 determines whether or not the engine 22 isstarted (the engine 22 is started by cranking the engine 22 with themotor MG1) (Step S800). The processing of Step S800 can be performed,for example, by reading information regarding determination of whetheror not the engine 22 is started through a routine (not shown) andwritten in the RAM (not shown). The processing of Step S800 isprocessing for determining whether or not the high controllability ofthe motors MG1, MG2 is requested. When the engine 22 is started, sincethe rotation speed Nm1 or the torque Tm1 (torque for cranking the engine22) of the motor MG1 is rapidly changed or the torque Tm2 of the motorMG2 is rapidly changed in order to secure the requested torque Td* dueto rapid change in torque output from the motor MG1 and applied to thedrive shaft 36 through the planetary gear 30, there is a possibilitythat the controllability of the motors MG1, MG2 is further degraded.Accordingly, in this modification example, determination is made whetheror not the engine 22 is started, thereby determining whether or not thehigh controllability of the motors MG1, MG2 is requested.

In Step S800, when the engine 22 is not started, determination is madethat the high controllability of the motors MG1, MG2 is not requested(is secured in a needed level), and the value of 1 is set as thepermission flags F1, F2. That is, the execution of the second PWMcontrol as the control of the inverters 41, 42 is permitted (Step S810),and this routine ends. When the engine 22 is started, determination ismade that the high controllability of the motors MG1, MG2 is requested(there is a possibility that the controllability of the motors MG1, MG2is further degraded), and the value of 0 is set as the permission flagsF1, F2. That is, the execution of the second PWM control as the controlof the inverters 41, 42 is inhibited (Step S820), and this routine ends.

As described above, in a case of executing the second PWM control as thecontrol of the inverters 41, 42, the controllability of the motors MG1,MG2 is likely to be degraded compared to a case of executing the firstPWM control. For this reason, in a case where the second PWM control isexecuted as the control of the inverters 41, 42 when the engine 22 isstarted, there is a possibility that the controllability of the motorsMG1, MG2 is further degraded and an overcurrent or an overvoltage occursin the inverters 41, 42. In this modification example, when the engine22 is started, determination is made that the high controllability ofthe motors MG1, MG2 is requested (there is a possibility that thecontrollability of the motors MG1, MG2 is further degraded), and as thecontrol of the inverters 41, 42, the execution of the second PWM controlis inhibited and the first PWM control is executed. With this, it ispossible to more sufficiently satisfy a request for the highcontrollability of the motors MG1, MG2. Specifically, it is possible tosuppress the occurrence of an overcurrent or an overvoltage in theinverters 41, 42.

In the hybrid vehicle 20 of the example or the modification examples, asdescribed in the permission flag setting routines of FIGS. 6 to 12, asthe condition for setting the value of 0 as the permission flag F1(inhibiting the execution of the second PWM control as the control ofthe inverter 41), the following conditions are used. In the permissionflag setting routine of FIG. 6, (A) the condition that the zero learningof at least one of the rotation position detection sensor 43 and thecurrent sensors 45 u, 45 v is not completed is used. In the routine ofFIG. 7, (B) the condition that an abnormality occurs in at least one ofthe rotation position detection sensor 43 and the current sensors 45 u,45 v is used. In the routine of FIG. 8, (C) the condition that the drivestate of the motor MG1 is rapidly changed is used. In the routine ofFIG. 9, (D) the condition that the vibration damping control by themotor MG1 is performed is used. In the routine of FIG. 10, (E) thecondition that an abnormality occurs in at least one of the currentsensor 55 a and the voltage sensor 57 a is used. In the routine of FIG.11, (F) the condition that the battery-less traveling mode is executedis used. In the routine of FIG. 12, (G) the condition that the engine 22is started is used. However, some or all of the conditions (A) to (G)may be used in combination. For example, in a case where all of theconditions (A) to (G) are used in combination, when at least one of theconditions (A) to (G) is established, the value of 0 may be set as thepermission flag F1. The permission flag F2 can be considered similarly.

In the hybrid vehicle 20 of the example, when the high controllabilityof the motor MG1 is requested, the execution of the second PWM controlas the control of the inverter 41 is inhibited (the first PWM control isexecuted); however, the execution of the second PWM control may belimited. For example, as the control of the inverter 41, the executionof the second PWM control other than the area 1 (see FIG. 5) in the areaof the second PWM control may be inhibited. Alternatively, the executionof the second PWM control other than a case where cruise traveling isperformed in the area of the second PWM control may be inhibited. Thecontrol of the inverter 42 can be considered similarly.

The hybrid vehicle 20 of the example includes the engine ECU 24, themotor ECU 40, the battery ECU 52, and the HVECU 70. However, some or allof the components may be constituted as a single electronic controlunit.

In the hybrid vehicle 20 of the example, although the battery 50 is usedas an electric power storage device, a capacitor may be used.

In the hybrid vehicle 20 of the example, although the boost converter 55is provided between the inverters 41, 42 and the battery 50, the boostconverter 55 may not be provided.

In the hybrid vehicle 20 of the example, the engine 22 and the motor MG1are connected to the drive shaft 36 coupled to the drive wheels 39 a, 39b through the planetary gear 30, and the motor MG2 is connected to thedrive shaft 36. However, as shown in a hybrid vehicle 120 of amodification example of FIG. 13, a motor MG may be connected to thedrive shaft 36 coupled to the drive wheels 39 a, 39 b through atransmission 130, and the engine 22 may be connected to a rotationalshaft of the motor MG through a clutch 129. As shown in a hybrid vehicle220 of a modification example of FIG. 14, a configuration of a so-calledseries hybrid vehicle may be made in which a motor MG2 for traveling maybe connected to the drive shaft 36 coupled to the drive wheels 39 a, 39b, and a motor MG1 for electric power generation may be connected to anoutput shaft of the engine 22. As shown in an electric vehicle 320 of amodification example of FIG. 15, a configuration of an electric vehiclemay be made in which a motor MG for traveling may be connected to thedrive shaft 36 coupled to the drive wheels 39 a, 39 b. In a case of theconfiguration of the electric vehicle 320, the motor ECU 40 can executethe permission flag setting routines of FIGS. 6 to 10 among thepermission flag setting routines of FIGS. 6 to 12.

An applicable embodiment is not limited to such a vehicle, and may beapplied to a drive device that is mounted in a mobile object, such as avehicle, or may be applied to a drive device that is embedded in afacility, such as a construction facility, not a mobile object.

The correspondence relationship between the primary components of theexample and the primary components described in “SUMMARY” will bedescribed. In the example, the motor MG2 corresponds to a “motor”, theinverter 42 corresponds to an “inverter”, the battery 50 corresponds toan “electric power storage device”, and the motor ECU 40 corresponds toan “electronic control unit”.

The correspondence relationship between the primary components of theexample and the primary components described in “SUMMARY” should not beconsidered to limit the components described in “SUMMARY” since theexample is solely illustrative to specifically describe the aspects ofthe present disclosure. That is, the present disclosure described in“SUMMARY” should be interpreted based on the description in “SUMMARY”,and the example is only a specific example of the present disclosuredescribed in “SUMMARY”.

Although the mode for carrying out the present disclosure has beendescribed above in connection with the example, an applicable embodimentis not limited to the example, and can be of course carried out invarious forms without departing from the spirit and scope of the presentdisclosure.

The present disclosure is usable in a manufacturing industry of a drivedevice and a vehicle, or the like.

What is claimed is:
 1. A drive device comprising: a motor for traveling; an inverter configured to drive the motor by switching a plurality of switching elements; an electric power storage device configured to transmit and receive electric power to and from the motor through the inverter; and an electronic control unit configured to: generate a first pulse width modulation signal of the switching elements by comparison of a voltage command of each phase according to a torque command of the motor and a carrier wave voltage and switch the switching elements with the first pulse width modulation signal, as a first pulse width modulation control; generate a second pulse width modulation signal of the switching elements based on a modulation factor and a voltage phase of a voltage according to the torque command and a pulse count per unit cycle of an electric angle of the motor and switch the switching elements with the second pulse width modulation signal, as a second pulse width modulation control, a switching frequency of the switching elements in the second pulse width modulation control being set to be smaller than a switching frequency of the switching elements in the first pulse width modulation control; and limit execution of the second pulse width modulation control when high controllability of the motor is requested rather than when the high controllability is not requested.
 2. The drive device according to claim 1, wherein the electronic control unit is configured to permit the execution of the second pulse width modulation control when the high controllability is not requested, and to inhibit the execution of the second pulse width modulation control when the high controllability is requested.
 3. The drive device according to claim 2, wherein the electronic control unit is configured to execute the first pulse width modulation control when a target operation point of the motor is outside a predetermined area even in a case where the high controllability is not requested and the execution of the second pulse width modulation control is permitted.
 4. The drive device according to claim 1, wherein the electronic control unit is configured to generate the second pulse width modulation signal of the switching elements such that, in the second pulse width modulation control, a harmonic component of a desired order is reduced and a total loss of loss of the motor and loss of the inverter is reduced more than in the first pulse width modulation control.
 5. The drive device according to claim 1, further comprising: a rotation position detection sensor configured to detect a rotation position of a rotor of the motor; and a current sensor configured to detect a current flowing in the motor, wherein the electronic control unit is configured to determine that the high controllability is requested when zero learning of at least one of the rotation position detection sensor and the current sensor is not completed.
 6. The drive device according to claim 1, further comprising: a rotation position detection sensor configured to detect a rotation position of a rotor of the motor; and a current sensor configured to detect a current flowing in the motor, wherein the electronic control unit is configured to determine that the high controllability is requested when an abnormality occurs in at least one of the rotation position detection sensor and the current sensor.
 7. The drive device according to claim 1, wherein the electronic control unit is configured to determine that the high controllability is requested when an amount of change per unit time of at least one of the torque command of the motor, a rotation speed of the motor, a voltage of the inverter, and a voltage of the electric power storage device is greater than a corresponding threshold.
 8. The drive device according to claim 1, wherein the electronic control unit is configured to determine that the high controllability is requested when vibration damping control by the motor is performed.
 9. The drive device according to claim 1, further comprising: a boost converter configured to boost electric power from the electric power storage device and to supply electric power to the inverter; a current sensor configured to detect a current flowing in a reactor of the boost converter; and a voltage sensor configured to detect a voltage on the inverter from the boost converter, wherein the electronic control unit is configured to determine that the high controllability is requested when an abnormality occurs in at least one of the current sensor and the voltage sensor.
 10. A vehicle comprising: the drive device according to claim 1; drive wheels that are connected to the motor and driven; an engine; a power generator configured to generate electric power using power from the engine; an inverter for a power generator configured to drive the power generator by switching a plurality of second switching elements; and a relay configured to perform connection and disconnection of the inverter and the inverter for a power generator to and from the electric power storage device, wherein: the electronic control unit is configured to control the inverter for a power generator by switching the first pulse width modulation control and the second pulse width modulation control; the electronic control unit is configured to determine that the high controllability of the motor and the power generator is requested in a case of performing traveling by disconnecting the inverter and the inverter for a power generator from the electric power storage device by the relay; and the electronic control unit is configured to limit the execution of the second pulse width modulation control when the high controllability of the power generator is requested rather than when the high controllability is not requested.
 11. A vehicle comprising: the drive device according to claim 1; drive wheels that are connected to the motor and driven; an engine; a motor generator; a planetary gear including three rotating elements, the three rotating elements of the planetary gear being connected to an output shaft of the engine, a rotational shaft of the motor generator, and a drive shaft coupled to an axle, respectively; and an inverter for a motor generator configured to drive the motor generator by switching a plurality of second switching elements, wherein: the electric power storage device is connected to the motor and the motor generator through the inverter and the inverter for a motor generator so as to transmit and receive electric power to and from the motor and the motor generator; the electronic control unit is configured to control the inverter for a motor generator by switching the first pulse width modulation control and the second pulse width modulation control; the electronic control unit is configured to determine that the high controllability of the motor and the motor generator is requested in a case of starting the engine by cranking the engine with the motor generator; and the electronic control unit is configured to limit the execution of the second pulse width modulation control when the high controllability of the motor generator is requested rather than when the high controllability is not requested. 